2021ApJ...910..160B

We performed deep observations to search for radio pulsations in the directions of 375 unassociated Fermi Large Area Telescope γ-ray sources using the Giant Metrewave Radio Telescope (GMRT) at 322 and 607 MHz. In this paper we report the discovery of three millisecond pulsars (MSPs), PSR J0248+4230, PSR J1207-5050, and PSR J1536-4948. We conducted follow-up timing observations for ∼5 yr with the GMRT and derived phase-coherent timing models for these MSPs. PSR J0248+4230 and J1207-5050 are isolated MSPs having periodicities of 2.60 ms and 4.84 ms. PSR J1536-4948 is a 3.07 ms pulsar in a binary system with an orbital period of ∼62 days about a companion of a minimum mass of 0.32 M_☉. We also present multifrequency pulse profiles of these MSPs from the GMRT observations. PSR J1536-4948 is an MSP with an extremely wide pulse profile having multiple components. Using the radio timing ephemeris we subsequently detected γ-ray pulsations from these three MSPs, confirming them as the sources powering the γ-ray emission. For PSR J1536-4948 we performed combined radio-γ-ray timing using ∼11.6 yr of γ-ray pulse times of arrival (TOAs) along with the radio TOAs. PSR J1536-4948 also shows evidence for pulsed γ-ray emission out to above 25 GeV, confirming earlier associations of this MSP with a >=10 GeV point source. The multiwavelength pulse profiles of all three MSPs offer challenges to models of radio and γ-ray emission in pulsar magnetospheres.